Data has been collected primarily using a depth measurement device, such as an echo-sounder, in combination with a GPS for horizontal positioning. Other survey methods, such as bathymetric LiDAR may also have been used. The survey method used in each body of water is shown in the [Bathymetry Index](https://geohub.lio.gov.on.ca/datasets/mnrf::bathymetry-index ). *[GPS]: Global Positioning System

Bathymetry of Lake Ontario has been compiled as a component of a NOAA project to rescue Great Lakes lake floor geological and geophysical data and make it more accessible to the public. The project is a cooperative effort between investigators at the NOAA National Geophysical Data Center's Marine Geology & Geophysics Division (NGDC/MGG) and the NOAA Great Lakes Environmental Research Laboratory (GLERL). was compiled utilizing the entire historic sounding data base. The entire historic hydrographic sounding data base from the U.S. and Canada, originally collected for nautical charting purposes, was used to create a complete and accurate representation of Lake Ontario bathymetry. The U.S. data primarily came from the NOS Hydrographic Survey Data. This and other bathymetric sounding data collected by the U.S. National Ocean Service's (NOS) Coast Survey and the U. S. Army Corps of Engineers was employed to construct bathymetric contours at 1 meter intervals from 1-10 meters depth and 2 meter intervals at depths greater than 10 meters. Compilation scales ranged from 1:10,000 to 1:50,000. Bathymetric sounding data collected by the Canadian Hydrographic Service (CHS) were employed to construct bathymetric contours at 1 meter intervals and compilation scales ranging from 1:1,000 to 1:30,000. Digitization of the bathymetric contours, merging of the bathymetric contour data sets, poster construction, and preparation of a CD-ROM, were accomplished at the NGDC. Multibeam bathymetric data collected by the University of New Brunswick's Ocean Mapping Group (UNB-OMG), with support of the Geological Survey of Canada (GSC) and the CHS, were kindly made available in gridded form. In the two areas where multibeam bathymetric data were available, no other bathymetric data were used in the compilations. In some areas all available Canadian and U. S. bathymetric sounding data, collected at different times on different survey expeditions, were used to derive the contours. The U.S. coastline used was primarily the GLERL Medium Resolution Vector Shoreline dataset (Lee, 1998). Where needed for more coverage, the NOS Medium Resolution Vector Shoreline for the Conterminous U.S. (1994) dataset was used. Coastlines from the CHS bathymetric sounding data field sheets were used to complete the Canadian coastline. Images were constructed using the publicly-available software Generic Mapping Tools (GMT).

The attribute table included in the dataset provides some limited metadata information that is specific to each lake. This includes the: * survey year * survey method * original map scale This dataset should be used for discovery of Bathymetry data. It provides no bathymetric information, but allows users to discover where bathymetry data exists and in what format. Related datasets: * [Ontario waterbody location identifer](https://data.ontario.ca/dataset/ontario-waterbody-location-identifier)

All available bathymetry and related information for Jack Fish Lake were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.

Bathymetry is the measurement of water depth in lakes. From the 1940s to the 1990s, the Ministry of Natural Resources and Forestry produced bathymetry maps for over 11,000 lakes across Ontario. The data can be used by the general public and GIS specialists for: * climate change modelling * fish monitoring and other ecological applications * hydrologic cycle modelling * recreational fishing maps * watershed-based water budgeting The maps were created using simple methods to determine lake depths. They were meant for resource management purposes only. Little effort was made to identify shoals and other hazards when creating these bathymetric maps. Since this data was collected, many constructed and naturally occurring events could mean that the depth information is now inaccurate, so these maps should not be used for navigational purposes. In many cases, these maps still represent the only authoritative source of bathymetry data for lakes in Ontario. __Technical information__ These maps are being converted to digital GIS line data which can be found in the [Bathymetry Line](https://geohub.lio.gov.on.ca/datasets/mnrf::bathymetry-line) data class. The [Bathymetry Index](https://geohub.lio.gov.on.ca/datasets/mnrf::bathymetry-index) data class identifies if GIS vector lines have been created and the location of mapped lakes. The historic paper maps have been scanned into digital files. We will add new digital files to this dataset if they become available. The digital files have been grouped and packaged by regions into 13 compressed (zipped) files for download. Note: package 99 contains scanned maps where the location shown on the map could not be determined.

All available bathymetry and related information for Frog Lake were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.

All available bathymetry and related information for Chain Lakes were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.

This spatial dataset represents the locations of aquatic resource area (ARA) line segments derived from corresponding line features in the Ontario Hydro Network. ARA line segments may represent a portion of a water body or an entire water body (such as a lake, river or stream). Attributes for each location may include: * physical characteristics such as water temperature and depth * fish species The ARA data classes are the authoritative source for generic spatial data related to fish species in Ontario. The data can be used for: * forest and fisheries management planning * municipal planning * natural heritage and land use planning * issuing work permits under the [Public Lands Act](https://www.ontario.ca/laws/statute/90p43), 1990 * issuing licenses under the [Fish and Wildlife Conservation Act](https://www.ontario.ca/laws/statute/97f41), 1997 * fulfilling public information requests There are additional sensitive data related to provincially tracked species and species at risk that are not available as part of this open data package. Distribution of sensitive species data is approved on a need-to-know basis. Requests should be sent to [geospatial@ontario.ca](mailto:geospatial@ontario.ca).

All available bathymetry and related information for Bridge Lakes were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.

All available bathymetry and related information for Island Lake were collected and hard copy maps digitized where necessary. The data were validated against more recent data (Shuttle Radar Topography Mission 'SRTM' imagery and Indian Remote Sensing 'IRS' imagery) and corrected where necessary. The published data set contains the lake bathymetry formatted as an Arc ascii grid. Bathymetric contours and the boundary polygon are available as shapefiles.